Abstract
Without warning, the relatively calm solar atmosphere can be torn asunder by brief and catastrophic outbursts of incredible energy, called solar flares, which occur in active regions, the magnetized atmosphere in and around sunspots. They are sudden and brief, usually lasting no more than 10 min, and rapidly increase the temperature of relatively small, Earth-sized region of the corona to temperatures as high as 20×106 K. As a result, solar flares can outshine the entire Sun in X-rays and extreme-ultraviolet radiation (Fig. 6.1). Solar flares are normally not detected in bright, visible sunlight, but they can be seen at visible wavelengths when focusing in on the red spectral line of hydrogen, the Balmer alpha transition at 656.3 nm.
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© 2009 Springer-Verlag Berlin Heidelberg
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Lang, K.R. (2009). Our Violent Sun. In: The Sun from Space. Astronomy and Astrophysics Library. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-76953-8_6
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DOI: https://doi.org/10.1007/978-3-540-76953-8_6
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-76952-1
Online ISBN: 978-3-540-76953-8
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